JP2011515138A - A dynamic planning tool for contrast-enhanced dynamic scanning in magnetic resonance imaging - Google Patents

Abstract

  The timing scheme of the breast dynamic contrast MRI scan is critical for any subsequent analysis or CAD. The present invention proposes a planning device configured to calculate a timing scheme for dynamic MRI examinations to be incorporated into either an MRI scanner or a breast analysis or CAD software package. Scheduled scans can be transferred to the scanner manually or using ExamCard. This plan can also be used as input for analysis or CAD software packages.

Description

  The present invention relates generally to the field of medical imaging. More specifically, the present invention relates to a dynamic planning tool for contrast dynamic scanning in magnetic resonance imaging.

  Magnetic resonance imaging (MRI) examination of breast cancer involves a dynamic contrast scan, where the intensity at each voxel of the acquired image as a function of time indicates the underlying pathology.

  During an image acquisition scan, a dynamic pre-contrast scan is performed, followed by intravenous injection of contrast agent. There are several types of contrast agents available, such as water that is administered orally to image the stomach and small intestine, although materials with specific magnetic properties can be used. Most commonly, paramagnetic contrast agents, usually gadolinium compounds, can be given as contrast agents. Gadolinium-enhanced tissue and fluid appear very bright on the T1-weighted image. This provides a high sensitivity for the detection of vascular tissue such as, for example, tumors and allows for the assessment of cerebral perfusion, for example in connection with stroke.

  Once administered, the contrast agent passes through the bloodstream until it reaches the tissue of interest such as breast tissue for the first time. And it augments the breast tissue for some time, eg 6-10 minutes. This enhancement is observed for a while by acquiring subsequent images using MRI. Typically, a stack of images or a time series of image volumes is acquired beginning 8 months and continuing for 8-10 minutes. In some cases, a maximum intensity, such as a peak appearing approximately 2 minutes after the start of the initial image data acquisition, can be observed, Kuhl CK, Mielcareck P, Klaschik S, Leutner C, Wardelmann E, Gieske J, Schild HH, Dynamic Breast MR Imaging: Are Signal Intensity Time Course Data Usage for Differential Diagnosis of Enhancing Relations? According to Radiology, 1999; 211: 101-110 (hereinafter referred to as Kuhl 1999), this maximum value correlates with a malignant tumor. Breast tissue enhancement can be observed for several minutes before and after the peak.

  In some cases no peak may be observed. The tissue that continuously grows during image acquisition or augmentation becomes nearly constant and a plateau is established.

  MRI scans are generally controlled by a timing scheme that has information about how image data should be collected in time, ie over a period of time, in an MRI system. In simplified terms, after excitation of a proton of an object by an RF pulse in MRI, a number of RF pulses or so-called RF profiles returning from the object are measured for a period of time, followed by the use of a Fourier transform to create an image. Is done. Different profiles contribute differently to the final image, for example the center of the profile space (ie k-space) contains the low spatial frequencies in the image. Data information in k-space is important for obtaining a desired image result. From an implementation point of view, k-space is a temporary image space where data from digitized MRI signals is stored during data acquisition. When the k-space is full, this means the end of the scan, but the acquired data can be processed mathematically to produce the final image.

  If a peak of maximum enhancement occurs, this will appear at some instant. Depending on the chosen k-space ordering, the peak may or may not coincide with when the center of k-space is acquired. The center of this k-space contains the image signal-to-noise and contrast information and thus contributes significantly to the acquired image. Therefore, it is not known whether a peak is visible in the image, but a visible peak is necessarily desired.

  The theory that the peak of maximum enhancement appears approximately 2 minutes after bolus injection can be replaced, for example, by pharmacokinetic modeling, which can optionally provide more knowledge about the augmented tissue. The present invention according to some embodiments can also be extended to include such pharmacokinetic modeling because acquisition is optimized for the model.

  The arrival time of the contrast bolus can be determined by an infusion protocol with information about the rate and amount of contrast agent infusion, and especially for patients with cardiac disorders, blood flow information that varies from patient to patient.

  Throughout this specification, the term “dynamic scan” refers to an MRI time series of image stacks or image volumes. One stack of images or one image volume is referred to as a “dynamic image data set” as part of such time series.

  In a dynamic MRI scan with a specific duration, for example when 80 seconds / dynamic image data set, ie 1 volume of image data is acquired every 80 seconds, the image data is sampled in k-space. Depending on what, it can be obtained differently in time.

  Data in k-space can be acquired in a variety of different orders as shown in FIGS. 1a-1c. FIG. 1a illustrates a Linear space encoding order in which data is acquired along a straight line moving from one side of k-space to the other. FIG. 1b illustrates a Centric space encoding order in which data is acquired along a straight line starting at the center of the outer k-space. FIG. 1c illustrates a Radial phase encoding order in which data is acquired along a straight line originating from a point in the center of k-space. Depending on the choice of timing scheme, the acquired image data should be analyzed differently.

  Currently, the entire scan sequence including the timing scheme with the start of dynamic scan, bolus injection, and later start of dynamic image data set is calculated manually. An estimate of how long it takes for the bolus to reach the breast and how long it takes for the tissue to grow is typically 2 minutes. Based on this time estimate, a second dynamic image data set may be acquired 2 minutes after the start of the bolus. The injector and image scanner are manually programmed with a calculated timing scheme. Manual calculation is a complicated procedure.

  Furthermore, a further problem with current manual approaches for calculating timing schemes relates to the fact that analysis software such as CAD software makes assumptions about the scan protocol used. Usually these assumptions are potential and many users are unaware of them. The scan protocol and associated ambiguous parameters can affect the MRI image data set obtained from subsequent image analysis of the acquired image data.

  Thus, current injector timing schemes are based on specific manually calculated scan protocols. When choosing a different protocol, the estimated scan protocol may be wrong, leading to a misclassification of the curve type, for example a plateau instead of a peak, and possibly a misdiagnosis.

  Thus, an improved planning device, graphical user interface, and usage thereof are advantageous, allowing increased flexibility, cost effectiveness, and reduced time consumption.

  Accordingly, the present invention preferably seeks to alleviate, mitigate, or eliminate one or more of the above deficiencies or disadvantages in the art, alone or in any combination, and a planning device according to the appended claims, By providing a graphical user interface and usage of the planning device, at least the above problems are solved.

  According to one aspect of the present invention, an apparatus for scheduling the timing of a dynamic contrast magnetic resonance image scan is provided. The apparatus is configured to receive user-defined parameters. Further, the apparatus is configured to calculate a timing scheme for the dynamic contrast magnetic resonance image scan based at least on the user-defined parameter.

  In accordance with another aspect of the present invention, a graphical user interface is provided for planning the timing of dynamic contrast magnetic resonance image scans. The graphical user interface is configured to receive user-defined parameters. Further, the graphical user interface is configured to calculate a timing scheme based on the user-defined parameter. Furthermore, the graphical user interface is configured to present the timing scheme to the user, for example on a display.

  In accordance with yet another aspect of the present invention, there is provided the use of an apparatus for calculating a timing scheme for dynamic magnetic resonance imaging of breast tissue for locating a tumor.

  According to some embodiments, a planning device is provided and configured to calculate a timing scheme for a dynamic MRI scan to be incorporated into either an MRI scanner or a breast analysis or CAD software package. Scheduled scans can be transferred to the scanner manually or using ExamCard. This plan can also be used as input for analysis or CAD software packages.

  The planning device according to some embodiments is simple to handle and facilitates the user to create an accurate scan and injection protocol in an error-free manner.

  Further, the timing scheme calculated by the planning device according to some embodiments can then be transferred to an analysis or CAD package.

  When communicating with an external device such as a scanner, the planning device may be configured to control the scan and infusion protocol for an individual patient, for example, in the case of a known cardiac disorder. In this way, several injection devices can be remotely controlled, for example by a scanner.

  These and other aspects, features, and advantages of the present invention will become apparent and elucidated from the following description of embodiments of the invention with reference to the accompanying drawings.

Figures 1a to 1c illustrate three methods for acquiring data in k-space. FIG. 1a illustrates a Linear space encoding order for obtaining k-space data. Figures 1a to 1c illustrate three methods for acquiring data in k-space. FIG. 1b illustrates a Centric space encoding order for obtaining k-space data. Figures 1a to 1c illustrate three methods for acquiring data in k-space. FIG. 1c illustrates a Radial phase encoding order for obtaining k-space data. FIG. 2 is a diagram of a graphical user interface according to one embodiment. FIG. 3 is a diagram showing simulations of various MRI scans. FIG. 4 is a diagram of a graphical user interface according to one embodiment. FIG. 5 is a diagram illustrating an apparatus according to an embodiment.

  Several embodiments of the present invention will be described in more detail below with reference to the accompanying drawings in order for those skilled in the art to be able to practice the invention. The invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. The embodiments do not limit the invention, which is limited only by the scope of the appended claims. Furthermore, the terminology used in the detailed description of specific embodiments illustrated in the accompanying drawings is not intended to limit the present invention.

  The following description focuses on embodiments of the present invention applicable to a planning tool for the calculation of timing schemes for dynamic MRI scans, in particular for breast tissue. However, the present invention is not limited to this application and can be applied to other tissue types or organs that may have a tumor, such as the prostate.

  The present invention according to some embodiments is important for breast dynamic contrast MRI and can be generalized to any MR dynamic scan.

  According to one embodiment, a planning device is provided having computer software for use with a breast MRI analysis or CAD system. The planning device is configured to calculate a timing scheme for the entire sequence of image scan and contrast agent injection. The planning device may have a graphical user interface for describing a sequence of events as a function of time based on a timing scheme. FIG. 2 illustrates an example of a graphical user interface representation of the planning device. The graphical user interface may have a window illustrating a plurality of dynamic image data sets 16 to be acquired of a patient organ or tissue. Through each dynamic scan, one or more dynamic image data sets may be acquired. The planning device allows the user to input multiple parameters. The user-defined parameters are, for example, injection speed, contrast agent concentration 11, total amount of contrast agent, injection delay 12, that is, injection is performed after acquisition of the first dynamic image data set of a plurality of dynamic image data sets is started. Infusion protocol parameters such as previous time can be affected. User-defined parameters may also include, for example, a dynamic image data set acquisition period 13, an arbitrary delay, such as the time between injection and acquisition 16 of multiple dynamic image data sets in a dynamic scan (hereinafter referred to as acquisition delay 14), phase Scan protocol parameters such as encoding order 15 may also be affected. The phase encoding order is the order in which the signal is sampled in k-space. The most common method is to acquire a signal along a unidirectional line. Various ways of acquiring data are possible, for example moving from left to right or from center to outside, or evenly distributing the lines.

  The planning device may be further configured to calculate at least infusion protocol or scan protocol parameters based on the at least one input user-defined parameter. For example, if you want to derive timing based on a given phase encoding order 15 and certain assumptions about cardiac function, and if the user has knowledge that, for example, the patient's heart pumps less blood than the average patient every second, This user-defined parameter can be entered into the planning device and the acquisition delay can be calculated by the planning device with respect to the term “parameter” above.

  The planning device may also be configured to present the calculated parameters on the display, such as in the graphical user interface of the planning device of FIG.

[Timing scheme calculation]
The timing scheme of the breast dynamic contrast MRI scan is critical for any subsequent analysis or CAD. This is also complicated to calculate. Parameters that affect the timing scheme include, for example, bolus size or amount of contrast agent, timing for contrast agent dynamics (eg, flow dynamics or target dynamics), necessary for the contrast agent to travel through the arteriovenous system to the target site Such as the start of acquisition of dynamic image data sets before and after contrast, and the phase encoding order of the MRI scan protocol.

  In one embodiment, the at least one calculated parameter relates to the timing scheme of the scanning procedure.

  In an actual implementation that provides a timing scheme, at least three parameters are required. That is, time to acquire one dynamic image data set, k-space ordering, and cardiac blood flow. The time to acquire one dynamic image data set can be calculated from multiple scanner parameters including, for example, various parameters specific to the field of view, resolution, number of slices, slice thickness, and MR pulse sequence. Instead of redoing the calculations to be performed by the scanner, the planning tool according to some embodiments is configured to receive parameters regarding the time to acquire one dynamic image data set. In another embodiment, the planning device is configured to read parameters from previous similar scans with a DICOM header.

  K-space ordering, such as the Centric spatial encoding order, relates to the part of the dynamic scan that has the strongest impact on the resulting dynamic image data set.

  The time from injection to the moment the contrast agent reaches the breast can be estimated by assuming a standard time, for example 30 seconds, or by modeling this process using patient weight and cardiac function. . Similarly, the occurrence of a peak in the second acquisition can be estimated to occur after 120 seconds.

  For example, if the user does not want contrast in the initial dynamic image data set, a time point is set before that no contrast agent can be administered. This is illustrated in FIG. 2 or 4 as 30 seconds before the middle of the first dynamic image data set.

  In addition, if the user wants to match the second dynamic image data set with the 2 minute peak, this requirement tells when the bolus injection should begin. This is illustrated in FIG. 2 or 4 as 120 seconds before the middle of the dynamic image data set acquisition.

  If there is a discrepancy between the two timings, the planning device is configured to present the problem to the user, for example by presenting problem related information on a display as illustrated in FIG. This discrepancy, for example, may also suggest that the delay proposed by the device is necessary between the start of contrast bolus injection and the acquisition of the second dynamic image data set. This provides an advantage over currently performed methods in which the user must manually check for potential discrepancies.

Table 1 illustrates how different parameters affect the timing scheme of dynamic MRI scans.

[Calculated parameters]
In one embodiment, the planning device may be configured to allow the calculated parameters to be used in subsequent image analysis of the acquired image data of the scan. This usability can be achieved by storing the calculated parameters in a memory from which an external device or system implemented by computer software means can read the calculated parameters therefrom. In this way, not only is the timing scheme for planning the exam calculated and presented, the information about the timing scheme can also be used for subsequent image analysis.

  For practical purposes, in the current solution, the scanner has only information about how long it should have been or how long it should be with a certain scan.

  In one embodiment, when the planning device is connected to a scanner, it is configured to read information regarding dynamic image data set acquisition from the scanner.

  In another embodiment, when the planning device is not connected to the scanner, but instead connected to another system such as a PACS system, a dedicated medical workstation or something, the information about the dynamic image dataset acquisition time is read. I can't do it. In this case, the planning device is configured to infer the dynamic image data set acquisition time, for example by using information about the dynamic scan performed in advance.

  In one embodiment, the parameter calculation may further be based on pre-calculated parameters, i.e. parameters calculated during the pre-scan, and user-defined parameters. Thus, the timing scheme for scanning can be obtained from pre-scan or from information available with the DICOM attribute of public or private.

[ExamCard]
In one embodiment, the planning device is configured to create an ExamCard that includes information about all scans. ExamCard is a complete description of an examination consisting of multiple scans, including timing and the like. This embodiment is particularly advantageous when the planning device is connected to or included in the scanner, in this case ExamCard does not have to be transferred to another device. However, if the planning device is not always connected to the scanner, the ExamCard can be transferred using any storage means such as a memory stick.

[Scan simulation]
In one embodiment, the planning device is further configured to make an estimate for cardiac blood flow and tissue type to simulate the entire scan. The contrast agent is administered intravenously and must pass through the heart and arteries to reach the breast tissue. The effect of this passage on the bolus as a function of time can be modeled as delay and bolus blur. If the cardiac blood flow is below average, this means that the patient has heart disease, but the delay and blur are longer. Blurring increases when vacuality in breast tissue decreases. An example of the output of such a simulation for various scans is shown in FIG. This can facilitate evaluation of whether the timing scheme calculated by the planning device is acceptable.

[Control of external devices]
Further, the planning device can be further configured to control external devices such as injectors and / or MRI systems based on user-defined and / or calculated parameters. The simplest interface between the scanner and the injection device is a panel on the scanner screen that is connected to the planning device to alert the user when a bolus is being injected. The next step is to position the scanner to send a trigger signal to the bolus injection. More complex interfaces can also be used such that the scanner is arranged to control the contrast bolus injection process parameters, such as bolus flow rate (volume / second) as a function of time, more benefits Bring.

[Procedure optimization]
In some embodiments, the planning device is configured to optimize the procedure. In a simple embodiment, the user enters all parameters. Therefore, no optimization is necessary.

  In the above case of “no optimization”, the user sets the dynamic image data set acquisition time to 90 seconds using, for example, linear phase encoding. The user also inputs the timing of contrast bolus injection at the start of the scan, for example. The planning device is configured to calculate when the first injection of the contrast agent bolus, the second injection, etc. are predicted in the breast tissue. Further, the planning device may be configured to show the results to the user regarding when the dynamic image data set having the strongest contribution in the middle of each acquisition of the dynamic image data set is acquired. This allows the user to understand and correct the acquisition as needed.

  However, in another embodiment, if the user wants to obtain a peak, for example, N seconds after reaching the bolus to the breast tissue, and enters only a few scan parameters, the planner needs the remaining necessary to obtain the optimum peak. Various scan parameters, such as contrast bolus start time and contrast bolus delay may be configured.

  Alternatively, the user may simply enter "I want to center the acquisition of the first dynamic image data set with the first pass of the contrast bolus through the breast tissue" and the planning device will then enter the scan sequence. The injection time can be calculated for.

  FIG. 4 illustrates one embodiment of a graphical user interface according to the present invention for use in connection with a planning device. Window 31 shows an overview of various events in time. The “Gaussian” curve 32 corresponds to linear phase encoding and the center of k-space is obtained at the center of the dynamic image data set acquisition 33. Similarly, the center of k-space is obtained at the center of the dynamic image data set acquisitions 34 and 35. In this example, this occurs 1 minute 10 seconds after the end of contrast agent injection. The text below the graph in window 31 displays the main parameters of this protocol so that an overview of everything clinically relevant is provided. This information can be printed for inclusion in, for example, protocol handbooks and / or ExamCard help information.

  FIG. 5 illustrates an apparatus 40 suitable for planning a timing scheme for dynamic contrast magnetic resonance image scanning. Device 40 is configured to receive 41 user-defined parameters. The apparatus may also be configured to calculate a timing scheme for the dynamic contrast magnetic resonance image scan based at least on the user-defined parameter.

  According to one embodiment, the timing scheme calculation is performed by calculating 43 at least one additional parameter based on the user-defined parameter, wherein the additional parameter is required to calculate the timing scheme. The

  Applications and applications of the above embodiments according to the present invention are various and include all fields where dynamic MRI scans are used.

  In one embodiment, the planning device is included in a medical workstation or medical system, such as a magnetic resonance imaging (MRI) system.

  A planning device according to some embodiments has computer software for performing the functions and features described above. In one embodiment, the computer software may reside on a computer readable medium.

  The invention can be implemented in any suitable form including hardware, software, firmware or any combination of these. However, preferably, the invention is implemented as computer software running on one or more data processors and / or digital signal processors. The elements and components of an embodiment of the invention may be physically, functionally and logically implemented in any suitable way. Indeed, the functionality can be implemented in a single unit, multiple units, or as part of other functional units. Thus, the present invention can be implemented in a single unit or can be physically and functionally distributed between different units and processors.

  Although the present invention has been described above with reference to described embodiments, it is not intended to be limited to the described embodiments. Rather, the present invention is limited only by the accompanying claims. Other embodiments than the above are equally possible within the scope of the appended claims.

  In the claims, the word “comprises / comprising” does not exclude the presence of other elements or steps. Furthermore, although individually listed, a plurality of means, elements or method steps may be implemented by eg a single unit or processor. In addition, although individual features may be included in different claims, they may be advantageously combined, and inclusion in different claims means that a combination of features is not feasible and / or not advantageous It does not suggest. In addition, the singular does not exclude the plural. Words such as “a”, “an”, “first”, “second” do not exclude plural forms. Reference signs in the claims are provided merely as a clarifying example and shall not be construed as limiting the scope of the claims in any way.

Claims (17)

An apparatus for planning the timing of a dynamic contrast magnetic resonance image scan, the apparatus comprising:
Receive user-defined parameters,
An apparatus configured to calculate a timing scheme for the dynamic contrast magnetic resonance image scan based on at least the user-defined parameter.   The apparatus of claim 1, wherein the calculation of the timing scheme is performed by calculating additional parameters based on the user-defined parameters, wherein the additional parameters are required by the timing scheme. The user-defined parameter is
An injection protocol having an injection rate, contrast agent concentration, total amount of contrast agent, or injection delay,
A scanning protocol having a duration of acquisition of the dynamic image data set, an acquisition delay, or a temporal k-space sampling mode, or
Patient characteristics with patient weight or blood flow,
The apparatus of claim 1, comprising information about   The apparatus according to claim 2, wherein the calculated additional parameter relates to an injection protocol or a scan protocol.   The apparatus of claim 1 included in an MRI analysis package, CAD system, or MRI scanner.   The apparatus of claim 5, wherein the timing scheme is utilized for subsequent image analysis.   The apparatus of claim 1, further configured to create an ExamCard.   The apparatus of claim 1, further configured to control the injector.   The apparatus of claim 1, wherein the calculation of the timing scheme can use a previously performed dynamic scan or parameters from a previously calculated timing scheme.   The apparatus of claim 1, further configured to visualize the timing scheme on a display.   The apparatus of claim 1, further configured to simulate a dynamic scan based on the timing scheme.   The apparatus of claim 1, wherein the timing scheme comprises a duration of acquisition of a dynamic image data set included in the dynamic scan, k-space ordering, or cardiac blood flow.   The apparatus of claim 1, further configured to read parameters for the timing scheme from an external device.   The apparatus of claim 1, wherein the user-defined parameter comprises information regarding user selection.   The apparatus of claim 14, configured to display user-defined parameters that conflict with each other in the calculated timing scheme. A graphical user interface for planning the timing of a dynamic contrast magnetic resonance image scan, the graphical user interface comprising:
Receive user-defined parameters,
Calculating a timing scheme based on the user-defined parameters;
A graphical user interface configured to present the timing scheme to a user.   Use of the apparatus according to claim 1 for the calculation of a timing scheme for dynamic magnetic resonance imaging scans of breast tissue to locate tumors.

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